Step 14: Final Comments
If you construct it right, the wiring has enough strength to stand on its own and the box provides adequate shielding.I've used my mixers in the car and elsewhere with no problems for several years.
However, if you're worried about the open wiring, then you can always cover the bare wires & resistors with electricians tape, just make sure not to break something in the process.
If you really wanted to make the mixer super rugged, you could fill the tin with epoxy, parafin or circuit-grade Silicone RTV.
Note: Don't use the regular Silicone RTV made for caulking and bathroom sealer. This stuff gives off acetic acid which will eat through your wires and ruin your project after a while. Circuit-grade Silicone RTV does not give off acid and is safe for wiring. I've read that GE Silicone II (available at home improvement stores) does not leach acid and also silicone RTV sold at automotive part stores labeled either 'Oxygen-sensor Safe' or 'Type B' should be OK.
I hope you are successful and get lots of good use out of this project, please let me know.